For example, there is disclosed a method for producing an α,β-unsaturated carboxylic acid from an olefin or an α,β-unsaturated aldehyde in a liquid phase in the presence of molecular oxygen and a palladium-containing catalyst in Patent Document 1. When the olefin is used as a raw material in this method, an α,β-unsaturated aldehyde is also produced, and hence this method can be applicable as a method for producing at least one of an α, β-unsaturated aldehyde and an α,β-unsaturated carboxylic acid depending on purposes.
Further, there is disclosed a method for producing methacrolein and methacrylic acid from t-butanol in a gas phase in the presence of molecular oxygen and a molybdenum-bismuth-iron based catalyst in Patent Document 2.    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-141,863    Patent Document 2: Japanese Patent Application Laid-Open No. 2004-130,261